docs: def transformChildrenToNative(self):
          """
          Recursively replace children with their native representation.
  
          Sort to get dependency order right, like vtimezone before vevent.
          """
          for childArray in (self.contents[k] for k in self.sortChildKeys()):
              for child in childArray:
                  child = child.transformToNative()
                  child.transformChildrenToNative()